Dual element air cleaner fuel evaporative loss control



Nov. 24, 1970 L. E. ADLER ETAL DUAL ELEMENT AIR CLEANER FUEL EVAPORATIVE LOSS CONTROL Filed 001;. 21, 1968 a a .7 A /d m8 N T O N E v N m fl AA W c LH LT ATTORNEY United States Patent 01 hoe 3,541,765 Patented Nov. 24, 1970 3,541,765 DUAL ELEMENT AIR CLEANER FUEL EVAPORATIVE LOSS CONTROL Leonard E. Adler, Detroit, and Thomas A. Nelson,

Birmingham, Mich., assignors to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Oct. 21, 1968, Ser. No. 769,154 Int. Cl. B01d 50/00 US. Cl. 55-316 1 Claim ABSTRACT OF THE DISCLOSURE An engine air cleaner contains two concentrically mounted ring type air filter elements, the inner one containing a bed of activated carbon to absorb excess fuel vapors from the carburetor fuel bowl and vehicle gasoline tank during the hot soak cycle of the engine, the vapors being purged into the engine during the normal air flow through the air cleaner, the inner filter being lower in height than the outer to provide a non-valved orificed air bypass of the inner filter of the air from the outer filter to the carburetor.

This invention relates, in general, to an internal combustion engine. More particularly, it relates to an air cleaner assembly for such an engine.

One of the primary objects of the invention is to provide an automotive type engine with an air cleaner assembly that will adsorb carburetor fuel bowl and vehicle gasoline tank vapors so that they are not discharged freely into the atmosphere, and yet will purge these vapors from the air cleaner assembly into the engine during the normal operation of the engine.

Another object of the invention is to provide a fuel vapor control of a type described above in which the adsorption-desorption functions of the air cleaner are performed without the use of valving.

A still further object of the invention is to provide an air cleaner assembly providing fuel vapor adsorptionpurge functions that are self-regulating in that the purging function automatically varies with the air flow to prevent excessive enrichening of the air-fuel mixture and an increase in exhaust emissions.

A still further object of the invention is to provide a fuel vapor emission control system for an automotive type engine consisting of: an air cleaner assembly having a pair of concentrically mounted air filters; the innermost of which consists of a bed of activated carbon operably connected to excess fuel vapors from the carburetor float bowl and vehicle gasoline tank for absorption of the vapors by the carbon particles during the hot soak cycle of the engine; and automatic desorption or purging of the fuel vapors from the carbon bed during normal operation of the engine inducing an air flow through both filters; the carbon bed filter being of lesser axial width than the outermost filter so as to provide a bypass area between the two filters; the bypass area constituting an orifice in parallel with the orifice defined by the carbon bed filter to effectively control the purge flow and the restriction to flow of the air into the engine carburetor.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating the preferred embodiments thereof, wherein:

FIG. 1 is a perspective view, with parts broken away and in section, of an air cleaner assembly embodying the invention;

FIG. 2 is an enlarged cross-sectional view of a detail of FIG. 1; and

FIG. 3 is an enlarged cross-sectional view of one-half of a modified air cleaner assembly.

FIG. 1 shows an essentially horizontally disposed air cleaner assembly having a conventional dish-shaped tray portion 10. It has a hollow interior closed by a fiat cover 12, with an annular seal element 14 therebetween. Tray portion 10 has essentially vertical wall portions 16 with an opening 18 at one portion constituting a fresh air inlet. A central axial opening 20 is provided in the bottom of tray portion 10 for a close fit over the air horn air inlet portion 22 of a conventional downdraft type carburetor 24, in a known manner. Cover 12 and tray 10 are secured to the carburetor by a bail member, not shown, secured in the carburetor induction passage and having a threaded portion projecting through cover 12 and engaged by a wing nut, in known manner.

Positioned within tray portion 10 are a pair of concentrically mounted ring-type filter elements 30 and 32 seated on portions of tray portion 10. The outermost filter element 30 constitutes a known type of radial flow, pleated paper element, perforated to permit the passage of air through while filtering foreign particles therefrom, in a known manner. Further details of construction and operation of the latter filter element are not given since they are known and believed to be unnecessary for an understanding of the invention. Sufiice it to say that the paper element is enclosed radially between annular perforated screens 34 having their edges buried sealingly in end annular plate members 36. The filter element 30 is of a height to sealingly engage the tray 10 and cover 12, thereby forcing all of the air passing through inlet 18 to pass through the pleated paper element on its way to the carburetor opening.

Spaced radially inwardly of pleated paper element 30 is filter element 32 consisting of a ring-like bed of activated carbon particles of a size suitable for the adsorption of hydrocarbons, in a manner to be described. The carbon particles are contained between a pair of mesh screens 40 having their edges sealingly imbedded in annular end caps 42 of plastic or similar material. The lower half portion of the carbon bed is provided with an annular groove or manifold 44 connected at its bottom by a hole 46 in end cap 42 to a fuel vapor line 48. The latter is a fuel vapor vent from the fuel bowl 50 of carburetor 24.

As shown in FIG. 1, it will be seen that the carbon filter element 32 is not as high; i.e., is of less axial width, than the pleated paper element 30. This provides a clearance space 52 between the element 32 and the air cleaner cover 12 through which air may flow from the pleated paper filter element 30 directly to the carburetor 24 bypassing the activated carbon filter element 32. In this case, the clearance space 52 is controlled in area to constitute an orifice in parallel with the orifice created by the restriction to flow through the carbon bed filter element 32. The area of the clearance space 52 is chosen to provide the desired restriction to assure the necessary purge flow through the activated carbon element without unduly restricting the overall air flow into the engine. Thus, the size of the bypass will control the overall pressure drop through the air cleaner assembly so that the fuel vapors will be purged into the engine, and yet all of the engine air requirements will be met.

FIG. 3 shows a modified form of carbon bed element. In this case, the inner end cap 54 is channel shaped in cross-section and constitutes a manifold 56 connected by a number of circumferentially spaced holes 58 to the carbon particle bed. The manifold on the opposite side is connected to the vapor containing conduit 48. In all other respects, however, the construction and operation of the air cleaner assembly remains essentially the same as that already described in connection with FIG. 1.

In operation, during the hot soak cycle of the engine when the engine is shut down and the temperature change becomes great enough so that considerable fuel in the carburetor fuel bowl vaporizes, the increased vapor pressure will force fuel vapors through the vent tube 48 into the annular groove 44 (FIG. 1) or manifold 56 (FIG. 3) of the activated carbon bed filter element 32. Subsequently, the vapors will flow over the carbon particles and form a film thereon and be adsorbed.

When the engine again operates, the suction created in the intake section of the carburetor creates a pressure differential between the atmospheric air at the inlet 18 to the air cleaner and the carburetor inlet, thereby inducing a How through both the pleated paper filter element 30 and the activated carbon bed element 32. The air flow across both element creates a pressure differential or pressure drop across them causing the fuel vapors to be desorbed or purged from the carbon particles for flow into the carburator proper.

The purging, of course, will be determined by the particles sizes, and the air flow, which will be determined by the engine speed, etc. The construction of the carbon bed element being of lesser axial height than the pleated paper element provides an effective purge control without the use of valving.

From the foregoing, therefore, it will be seen that the invention provides a fuel vapor emission control sys tem in the air cleaner assembly for an internal combustion engine that effectively stores fuel vapors emitted by the carburetor fuel bowl, and that during normal operation of the engine, the fuel vapors are purged from the air cleaner assembly into the engine in a manner such that the overall fuel ratio of the engine is relatively uneffected since clean air is bypassed around the fuel vapor absorbing element. It will also be seen that the purge function and timing of the system described will be controlled by the size of the carbon particles utilized, the configuration of the activated charcoal bed filter, and the variance in air flow through the bed controlling the pressure drop thereacross.

While the invention has been illustrated and described in its preferred embodiments, it will be clear to those skilled in the arts to Which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention. For example, the vapor vent tube 48 from the carburetor could be branched so as to include vapors from the vehicle gasoline tank.

What is claimed is: 4

1. An engine air cleaner assembly comprising an essentially horizontal disposed hollow annular closed housing having an ambient air inlet in the side thereof, air outlet means in a central portion of said housing, and a pair of radially spaced annular filter elements concentrically mounted in said housing, the radially outer element having essentially the same axial width as said housing forcing all airflow from said inlet therethrough, the radially inner element consisting of a bed of activated carbon for the adsorption and desorption of hydrocarbon vapors threby and therefrom, said inner element being of less axial Width than the outer element providing a restricting axial clearance defining an orifice between said inner element and housing combination with the radial space between said elements for a controlled flow of air therethrough from said outer filter bypassing said inner filter, and fuel vapor containing means connected to and discharging excess fuel vapor into said inner filter under conditions of engine hot soak whereby said fuel vapors are adsorbed by said carbon, the flow of air through said outer filter towards said outlet purging said inner filter of said fuel vapors, said inner element having an annular manifold formed therein and receiving said fuel vapors therein, said manifold defining a surface area of activated carbon particles exposed to said fuel vapors.

References Cited UNITED STATES PATENTS 2,122,111 6/1938 Poelman et a1. -316 2,400,180 5/ 1946 Venable 55-498 2,608,269 8/1952 Briggs 55-316 2,717,585 9/ 1955 Bradshaw.

2,996,145 8/ 1961 Thornburgh 55-498 3,171,726 3/1965 Roney et al 55-387 3,186,391 6/1965 Kennedy 55-482 3,189,179 6/1965 McMichael 210-315 3,221,724 12/1965 Wentworth 123-136 3,368,326 2/1968 Hervert 123-136 3,448,731 6/ 1969 Daigh 123-120 FRANK W. LU'ITER, Primary Examiner B. NUZICK, Assistant Examiner US. Cl. X.R. 

